Would love to hear any feedback. I've been super interested in how well-designed web apps and visualizations can communicate things like probability, which I think is very hard to intuit for many of us.
The most surprising thing I learned from the tool was just how bad your payouts usually were even if you cut the pool of numbers to pick from in half (by using the "Custom" option).
Also, at one point I messed up which pattern on Mega Millions tickets were winners. Something about that big X in a separate column just subconsciously seemed like it was showing winners. Perhaps dashes vs checks or groupings winning and non winning tickets together.
It won't make an impact on the odds of your tickets coming up as winners, unless they have a bug in their simulation. In the real world the probability of single versus multiple jackpot winners might vary with number choices, but they've already said they're assuming a single jackpot winner.
One suggestion I would make is allowing the random numbers selected by the user to be random for each draw. I understand in the scheme of things that it doesn't make difference to your odds but that's a strategy that some people play.
It would also be cool to track how many other people chose the same numbers that you did and then divide the jackpot winnings by that amount of people.
Another thing (I'm really just giving you a todo list of things that I had) was to organise the number selectors to mirror the pattern on the lottery tickets. People have very different approaches, picking columns, going over 31, sequences and you could track the user behaviour behind number selection.